@ Butch_M: You're probably right - but do you know what those requirements are? In terms of colour space, jpg compression, ppi etc? I can't seem to find any guidance on the Blurb site so was wondering if anyone over here might have known.

@Dorin: The controls for PDF export can be found as follows: within the book module, at the very top of the right panel, you can choose whether to create a book for blurb or PDF. If you change this to PDF, you will see another set of options for things like jpg qulaity, ppi, colour space etc.

My intention is to set up those PDF options to exactly match what Lightroom would upload to Blurb, for proofing purposes and for some troubleshooting that I'm doing.

I thought of that already John, but sadly it doesn't work that way. Unfortunately, even with Blurb selected in the book settings, the Export to Book in the left hand panel is still affected by changes made to the pdf options. It doesn't revert back to whatever the original settings were.

I did the following:

1. With Blurb selected I exported a PDF using the button on the left hand panel.

2. I changed from Blurb to PDF and dropped the jpg quality and ppi to low values (without noting the original values-oops!). I exported another PDF and as expected, the file size and image quality where noticeably smaller / worse.

3. I then changed back to the Blurb option in the book settings panel and I exported a third PDF using the button on the left hand panel. I expected this to match the first PDF in terms of file size and quality, but in fact this PDF was still small and crappy.